Roots: Mary Shelley's The Last Man, Jason and the Argonauts (an army of living skellingtons!) and Ezekiel 37: 1-14 (the 'valley of dry bones' story). Hamlet ("Alas, poor Yorick!") Alice's Adventures in Wonderland (The Doctor compares Tox to the March Hare). The four Gospels' account of the Crucifixion ("Look at that Golgotha!"), Dante's Divine Comedy (the Doctor says to Mary "You've now seen the seventh circle") Stronghaven sounds like something out of A Game of Thrones. Exodus 2:22 ("Strangers in a strange land"). Flash Gordon (1980) and Queen's title song ("Despatch the flybots to bring back their bodies") The Doctor sings the negro spiritual Dem Dry Bones.

Technobabble: Psychic isotopes live through bone matter and are susceptible to psychic pulses.

Dialogue Disasters: "'Ello, skullface - you want some?"

Double Entendres: There's no story sober enough to overcome the prurient potential of a concept called a "Bone Lord."

Continuity: The frontier world Draxine is a tenth-generation Earth colony, previously thought by the Doctor to be peaceful; its main continent is Zelonia, and it has only one moon. Quailerbeasts are a native (domestic?) animal. Technology includes hovering microphones and 'hoversentries' (nicknamed "flybots" by the Doctor). Carrying weapons has been banned for centuries, although the soldiers use a form of blaster.

Zelonia's twin cities were the warring states of Stronghaven, located within a great dome at the foot of cliffs and previously led by the assassinated President Karnex, and the former city Garrak, led by the seemingly late President Valak Harmon. Before its destruction Garrak was known for its great fountains and Tiffany lamps (according to the Doctor), had hovercars and used microchips for its social security, while Stonehaven used DNA profiling.

President Valak Harmon was rumoured to have supernatural powers and was reputed to be the focus of a city-wide death cult. His former rival Karnex was the predecessor of Stronghaven's new president, Vallan.

Karnex's 'Bone Lord' is the culmination of the Lifespan Project, an investigation into storing and using one's psychic cloud and thereby 'cloning' or backing it up. Karnex talks of his psychic cloud as being his "soul." The bomb Karnex ordered on Garrak (and his scientists there) was laced with the same psychic isotope he used to duplicate his mind before his assassination, allowing him to directly link to the bones of Garrak's dead.

Mary signs herself Godwin in episode two and Shelley in episode one. Despite herself, she finds that she is falling for the Doctor.

The Doctor uses his sonic screwdriver to re-resonate a skull's speech (the orifices are all wrong for proper speech) He still has a strand of duckwood weed stuck between his toes from their last adventure (see: Untelevised Adventures).

Untelevised Adventures: The Doctor picked up some Oolong in Peking in either 1893 or 1983 (given the name, perhaps the former?)

Mary has been with the Doctor for 'weeks', and they recently visited the planet Mayhem which, despite the Doctor's earlier assurances that it was a world of serenity, proved to have an apt name.

Future History: Other Harmons include Ramirez Harmon, president of Mexico in 2017, Azac Harmon, president of Tigon III in the Tangiers Spiral

Location: Zelonia, Draxine, including the cities Garrak and Stronghaven.

Links: The Doctor says "You've tied me up tighter than a Plutonian tax collector" (The Sun Makers) He mentions to Mary and Nia that he used to have a flying car with a "great number plate." (Invasion of the Dinosaurs, Planet of the Spiders) and tells President Vallon that he was once accused of assassinating a president himself. (The Deadly Assassin.) The Doctor recalls the Cybermen (The Silver Turk) and the witches (The Witch from the Well)

The Bottom Line: "A nice large open space - what's the worst they could do, some redecorating?"

A straightforward adventure - it's a base under siege with a mad scientist in tow, but in places a little histrionic and very silly (whoever thought up the term Bone Lord?). The mystery angle is engaging, though the technobabble is in overdrive, and once the, er, Bone Lord manifests, the scares that were trying to come through in earlier scenes just dissipate under a surfeit of panto 'Fee Fi Fo Fum' shouting. Which is a shame, if this is the last we'll hear from Mary, and the Doctor seemed to be having fun most of the time. A bit ragged, really. But more of Mary - perhaps even in a farewell Companion Chronicle, wouldn't be unwelcome.